1. Field of the Invention
The present invention pertains to means and methods for treating tumors, and more particularly malignant tumors, in the bodies of animals, such as humans, and more particularly, it pertains to means and methods which utilize the application of a controlled heat source to the tumor volume to cause or aid in the cause of its necrosis.
2. Description of the Prior Art
In the treatment of malignant tumors in humans, it is well known that the controlled application of heat can be used to kill the malignant tumor cells. Being able to apply such heat to the tumor volume for a sufficient period of time and at an intensity to cause necrosis of the malignant cells without severely damaging the surrounding healthy tissue of the patient has always been a problem. Typically, by using ultrasound and electromagnetic heating techniques, heat can be radiated from the surface of the skin to a depth of about 3 cm. Such electromagnetic heating has been combined with radiation treatment for tumors to achieve some satisfactory results, and various configurations of prior art devices have been used in such prior art cancer treatment methods.
Most of the prior art hyperthermia treatment apparatus are comprised of non-invasive devices for use on the skin surface; however, because of the depth limitations of surface heating methods, invasive devices have also been utilized in the prior art to provide the heat source at the tumor site. Thus, in U.S. Pat. No. 4,154,246 to LeVeen a tuned coil is disclosed which is capable of being inserted into the tumor volume whereby the external application of a strong electromagnetic field creates electromagnetic radiation from the coil which is presumably sufficient to cause necrosis of the tumor.
U.S. Pat. No. 4,106,488 to Gordon discloses a process wherein minute ferromagnetic particles are placed in the tumor volume and then are inductively heated by subjecting them to a high frequency alternating electromagnetic field. These particles can, in addition to their use as radiating heat centers, also incorporates specific radioisotopes or tumor specific antibodies which are arranged to be released upon the generation of the heat to further aid in destroying the malignant cells.
U.S. Pat. No. 4,292,960 to Paglione discloses an invasive device which is adapted to generate microwave energy and which also includes radioactive material for application to the internal organs of the human body.
Finally, U.S. Pat. No. 2,102,270 to Hyams discloses a device wherein a tiny electrode is inserted into the tissue of a body and then a strong high frequency electrical current is generated between the electrode and an external electrode so as to pass an alternating current through the body in a narrow path to perform electrosurgical operations of the like.
Additionally, hyperthermia treatment of tumors has been done by connecting a pair of stainless steel tubes to a high frequency power source, and inserting the tubes into the tumor. Current passing between the tubes thus passes through the tumor to destroy the malignant cells thereof. However, the current also passes through the patient's flesh at portions of the tubes other than in the tumor volume, and therefore these devices have not proved to be too useful since they can cause significant damage to the healthy tissue of the patient.
Another conventional method of treating malignant tumors through the use of radioactive materials is to insert a catheter having an axial passage into the patient so that it passes into the tumor volume. A tube containing a number of radioactive seeds is then inserted into the axial passage of the catheter until the seeds are located adjacent the tumor site. The tubular insert is then left in the patient for a predetermined amount of time in order to permit the radioactivity to cause necrosis of the tumor cells.